Modern memory arrays include a very large number of memory cells that are arranged in columns and rows. Each column is connected via bit-lines to a read circuit and a write circuit. These modern memory arrays are expected to be fast, error free and to consume a minimal amount of power.
However, voltage based sensing is relatively slow, especially in large memory arrays.
Differential current sensing facilitates fast reading of relatively large memory arrays but is error prone, is very sensitive to process variations and noises. It also consumes a large amount of power.